A typical window covering is a blind or a curtain. When the covering is positioned to be placed over a window, a covering support is mounted in the window frame. The window frame supports the glass or other transparent material used for the window. The covering support supports a blind or a curtain, which can be used to prevent or permit viewing through the window as desired.
Major problems exist with window covering supports. Generally, a narrow covering support provides the best mounting capability for within the window frame. However, the narrower covering supports are not always substantial enough to brace heavier weight window coverings.
Furthermore, it is difficult to provide a narrow support for window coverings on a large window with a large expanse of glass. The weight of the window covering, needed to traverse a large window, almost always mandates a substantial covering support. However, substantial covering supports may not be narrow enough to be mounted within the window frame. The covering support must be strong and capable of holding the window covering, whatever its weight. 
With a covering support, width and strength are generally in direct proportion to each other. A sacrifice in width of a covering support usually leads to a corresponding sacrifice in strength. Concentration on strength usually leads to a covering support, which is too wide to be mounted flush within the window frame.
Thus, it is very desirable to provide a strong covering support, that is narrow enough to allow mounting within the window frame. This strong covering support must be able to support a heavy window covering, while, at the same time, it must fit flush within the window frame.
Even if such a covering support can be developed, the curtain or the blind therein must be operable. In other words, it is very desirable for the window covering support to facilitate the positioning of window treatment to allow or prevent viewing through the window.
Thus, the window treatment support also functions as a positioning device for the window treatment. Typical of the prior art positioning devices are the side pull cord devices. These cords are known to be safety hazards, especially for small children. A small child can playfully, accidentally, or purposely wrap that cord around his or her neck. If the cord is then shortened by the mechanism in the positioning device, a strangulation can occur, which can result in death. 
These positioning devices are typically at the end of the window covering support. Such a location for the positioning device makes it very attractive to a small child. It is very desirable to provide a suitable and durable positioning device for a window covering.
Durability is also a required or desired advantage of implements or positioning devices used to cover or uncover a window, as desired. The longer a device will last and function properly, the more acceptable it will be to consumers.
It is, therefore, very desirable to provide a positioning device, which minimizes danger, especially for a small child, while at the same time, providing the desired reliability and durability.